Oil extraction method and composition for use in the method

ABSTRACT

A composition is disclosed for aiding extraction of an emulsified oil from an oil and water emulsion. The composition includes silicon containing particles at a level of 0.1 wt. % to 30 wt. %; an emulsifying agent at a level of 1 wt. % to 30 wt. %; and water at a level of 40 wt. % to 99 wt. %. A method of extracting oil from an oil and water emulsion in a material is also disclosed. The method includes the steps of (a) dispersing silicon containing particles into the material using a mechanical blending device; and (b) separating the oil from the material. A method of extracting oil from an oil and water emulsion in a material is also disclosed. The method includes the steps of (a) providing a dispersion of silicon containing particles in water; (b) metering the dispersion into the material; and (c) separating the oil from the material.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.14/804,796 filed Jul. 21, 2015, which is a continuation of U.S. patentapplication Ser. No. 13/801,296 filed Mar. 13, 2013, now U.S. Pat. No.9,090,851.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH

Not Applicable.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The invention relates to compositions and methods for aiding theextraction of an emulsified oil from an oil and water emulsion.

2. Description of the Related Art

Most commercial corn oil is produced by front end fractionation of corngerm during the wet mill corn process. Recently, a new source of cornoil has arisen as a by-product of the dry-mill process used in theethanol industry. Dry milling is a process requiring less energy andless capital investment than wet-milling. Though corn oil captured atthe tail-end of a dry mill process is not suitable for food use, it canbe used as a biodiesel feedstock.

In the dry-mill ethanol process, yellow dent corn is milled, liquefiedand sent to a fermenter. Enzymes and yeast are added to convert starchinto ethanol, which is subsequently distilled off. This leaves a slurrycalled whole stillage. Whole stillage, which contains a concentrated oilfraction, is then separated via centrifugation into liquid and solidfractions called thin stillage and wet cake respectively. While part ofthe thin stillage is recycled to help liquefy the milled corn, the restis concentrated via evaporation into thick stillage (or syrup), which isdried and mixed with the wet cake to form distillers' dried gains withsolubles (DDGS). This is sold as cattle feed and is a good source ofprotein.

Due to the concentrating effect dry-milling has on the oil fraction,corn oil extracted from thick stillage has become a profitableco-product for the ethanol industry. Although removing corn oil lowersthe energy density of DDGS, some studies suggest that high oil contentin DDGS interferes with milk production in dairy cattle, and leads toundesirable pork bellies in swine. Therefore, removing some of the oilnot only leads to a valuable co-product, but also may improve DDGSquality.

Current methods of extracting corn oil from thick stillage includesolvent extraction (often hexane) and decantation. Hexane extraction,though effective, is energy intensive and requires a large amount ofcapital investment. Decantation requires little capital investment andhas the potential of being just as effective as hexane extraction.

Decantation, using centrifuges takes advantage of the density differencebetween the oil and the aqueous phase to create buoyant force on the oilsuspended in solution. In order for the buoyant force to be strongenough to overcome the interfacial interactions and surface frictionacting on the oil, individual oil droplets must be large enough so thatsufficient force can be generated. The current horizontal decanters usedin industry can separate particles as small as twenty micrometers indiameter. The success of current corn oil decantation is highlydependent on upstream processing conditions. Plants using hightemperature, high or low pH, smaller grind, and long periods ofretention tend to have increased oil yields.

However, there still exists a need for improved methods for recoveringcorn oil from byproducts of the dry-mill process used in the ethanolindustry.

SUMMARY OF THE INVENTION

The present invention addresses the foregoing needs by providing acomposition for aiding extraction of an emulsified oil from an oil andwater emulsion. The composition includes silicon containing particles ata level of 0.1 wt. % to 30 wt. %, an emulsifying agent at a level of 1wt. % to 30 wt. %, and water at a level of 40 wt. % to 99 wt. %.

The invention also provides a method of extracting oil from an oil andwater emulsion in a material. The method includes the steps of (a)dispersing silicon containing particles into the material using amechanical blending device; and (b) separating the oil from thematerial.

The invention also provides a method of extracting oil from an oil andwater emulsion in a material. The method includes the steps of (a)providing a dispersion of silicon containing particles in water; (b)metering the dispersion into the material; and (c) separating the oilfrom the material.

The invention also provides a method of extracting oil from an oil andwater emulsion in a material. The method includes the steps of (a)providing an emulsified and/or suspended dispersion of siliconcontaining particles in water; (b) metering the dispersion into thematerial; and (c) separating the oil from the material.

These and other features, aspects, and advantages of the presentinvention will become better understood upon consideration of thefollowing detailed description, drawings, and appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a process flow diagram showing a dry-mill ethanol process.

FIG. 2 is a process flow diagram showing one version of a method of oilextraction according to the invention.

FIG. 3 is a process flow diagram showing another version of a method ofoil extraction according to the invention.

FIG. 4 is a process flow diagram showing yet another version of a methodof oil extraction according to the invention.

Like reference numerals will be used to refer to like parts from Figureto Figure in the following description of the drawings.

DETAILED DESCRIPTION OF THE INVENTION

To provide context for the invention, FIG. 1 shows an example a dry-millethanol process. Corn is fermented, and ethanol is distilled off. Thisleaves whole stillage which is separated via centrifuging into a solidfraction and a liquid fraction called thin stillage. The thin stillageis concentrated via evaporation into thick stillage, which can beprocessed in a centrifugal decanter to separate out the corn oil.

In thick stillage, oil is likely present in four forms: (1) oil-in-wateremulsion stabilized by proteins and phospholipids; (2) minute oildroplets that are bound in a matrix of intact and denatured hydrophobicproteins and cell wall components; (3) oil in intact oil bodies releasedfrom broken cells; and (4) oil in intact oil bodies in the unbrokenendosperm and germ particles. The upstream processing conditions(temperature, pH, etc. . . . ) in the ethanol plant will determine thedistribution of oil among these four forms, thus altering the ability ofthe decanter (e.g., a centrifugal decanter) to separate out the oil.

Oil bodies are the biological structures in which oil, in the form oftriglycerides, is contained within the cells of certain seeds. Theirpurpose is to prevent oil coalescence even in the event of extremedesiccation, an essential step in seed maturation. Though oil bodies areoften packed very tightly, they are prevented from coalescing by ahighly specialized surface active protein called oleosin. Oleosin isstrongly anchored on the surface of the oil body by a long hydrophobicportion. This portion is folded into a hairpin like structure andextends into the oil. On either side are amphiphilic portions whichextend over the surface of the oil body, and act to shield the oil bodyfrom coalescence via steric and electrostatic hindrance. The estimatedsize of oil bodies in corn germ is 0.3-1.5 micrometers, significantlysmaller than the minimum size requirement for horizontal decanters.Thus, significant coalescence must occur before successful decantation.

Coalescence of two oil droplets in the thick stillage can be broken intotwo steps. First, the surface of two oil droplets must come into contactwith each other. For this to happen, the oil droplets have to be mobileand at least part of the surface must be free of debris that wouldstericly hinder their progression towards one another. The second steprequires that droplets actually coalesce once they come into contactwith each other. This depends on the stability of the droplet resultingfrom biological surfactants (i.e., oleosins and phospholipids). If thedroplet is completely covered by intact oleosins, the likelihood ofcoalescence is minimal.

The present invention breaks the oil-in-water emulsion that isstabilized by proteins and phospholipids such that significant corn oilcoalescence can occur before decantation. The oil-in-water emulsion canbe present in whole stillage, and/or thin stillage, and/or thickstillage in the dry-mill ethanol process.

Referring now to FIG. 2, there is shown a process flow diagram showingone version of a method of oil extraction according to the invention. Inthe method of FIG. 2, silicon containing particles from sources 12, 14,16 are added to the whole stillage, and/or the thin stillage, and/or thethick stillage, and dispersed by mechanical blending. A mechanicalblending device can be used for the dispersion. The mechanical blendingdevice can be selected from a dry blending hopper or a tri-blender.Physical addition of the silicon containing particles is also suitable.Any combination of the sources 12, 14, 16 can be used in the method ofFIG. 2. The addition of the silicon containing particles leads tosignificant corn oil coalescence before separation of the corn oil bycentrifuging or decantation. This increases the amount of corn oilrecovered during separation which can be accomplished using variousmeans such as centrifuging and/or decantation.

In the method of FIG. 2, non-limiting examples of the silicon containingparticles include silica, talc, clay, quartz, diatomaceous earth, andmixtures thereof. The silicon containing particles can be precipitatedor fumed. The silicon containing particles can be hydrophilic orhydrophobic. Preferably, the silicon containing particles areprecipitated hydrophilic silica particles. The silicon containingparticles can have an average particle size of less than 100micrometers, more preferably an average particle size of less than 50micrometers, and most preferably an average particle size of less than20 micrometers. Silica nanoparticles may be beneficial. One role of thesilicon containing particles is to disrupt the emulsion produced by thebiological surfactants allowing the oil to coalesce. The addition ofsilicon containing particles improves the oil extraction yielddramatically over centrifuging alone. In one version of the invention,the sources 12, 14, 16 only include silica particles.

While corn oil extraction is shown in FIG. 2, the method is suitable forthe extraction of other oils that are emulsified. For example, the oilcan be a vegetable oil, an animal fat, petroleum oil, and mixturesthereof. The vegetable oil and the animal fat may be emulsified by abiological surfactant comprising phospholipids and proteins.

Referring now to FIG. 3, there is shown a process flow diagram showinganother version of a method of oil extraction according to theinvention. In the method of FIG. 3, various compositions of theinvention are added to the whole stillage, and/or the thin stillage,and/or the thick stillage such that significant corn oil coalescence canoccur before separation of the corn oil by centrifuging or decantation.This increases the amount of corn oil recovered during centrifugingand/or decantation.

In the method of FIG. 3, dispersions of silicon containing particles inwater are contained in vessels 22, 23, 24. Metering devices, which inone non-limiting example can be pumps 26, 27, 28, meter the dispersionsof silicon containing particles into the whole stillage, and/or the thinstillage, and/or the thick stillage. Any combination of the vessels 22,23, 24 can be used in the method of FIG. 3. The addition of the siliconcontaining particles leads to significant corn oil coalescence beforeseparation of the corn oil by centrifuging or decantation. Thisincreases the amount of corn oil recovered during separation which canbe accomplished using various means such as centrifuging and/ordecantation.

In the method of FIG. 3, the silicon containing particles in thedispersions are preferably selected from silica, talc, clay,diatomaceous earth, and mixtures thereof. The silicon containingparticles can be precipitated or fumed. The silicon containing particlescan be hydrophilic or hydrophobic. Preferably, the silicon containingparticles are precipitated hydrophilic silica particles. The siliconcontaining particles can have an average particle size of less than 100micrometers, more preferably an average particle size of less than 50micrometers, and most preferably an average particle size of less than20 micrometers. Silica nanoparticles may be beneficial.

The silicon containing particles can be present in any of thedispersions at a level of 0.1 wt. % to 30 wt. %, more preferably, alevel of 5 wt. % to 15 wt. %, and most preferably, at a level of up to15 wt. %. The upper level of silicon containing particles in thedispersion can be limited by viscosity. Water can be the remainder ofthe dispersions. Optionally, the dispersions can include less than 1% ofa biocide/preservative to prevent the growth of micro-organisms andthereby improve the shelf-life of the dispersions. The siliconcontaining particles can be dispersed under high shear and transferredinto the vessels 22, 23, 24. The silicon containing particles can bedispersed using milling, homogenizing, or ultrasonic means.

While corn oil extraction is shown in FIG. 3, the method is suitable forthe extraction of other oils that are emulsified. For example, the oilcan be a vegetable oil, an animal fat, petroleum oil, and mixturesthereof. The vegetable oil and the animal fat may be emulsified by abiological surfactant comprising phospholipids and proteins.

Referring now to FIG. 4, there is shown a process flow diagram showingyet another version of a method of oil extraction according to theinvention. In the method of FIG. 4, a composition of the invention isadded to the whole stillage, and/or the thin stillage, and/or the thickstillage such that significant corn oil coalescence can occur beforeseparation of the corn oil by centrifuging or decantation. Thisincreases the amount of corn oil recovered during centrifuging and/ordecantation.

In the method of FIG. 4, dispersions of silicon containing particles inwater are contained in vessels 42, 43, 44. A suspending agent and/or anemulsifying agent is also contained in vessels 42, 43, 44. Meteringdevices, which in one non-limiting example can be pumps 46, 47, 48,meter dispersions of silicon containing particles and the suspendingagent and/or the emulsifying agent into the whole stillage, and/or thethin stillage, and/or the thick stillage. Any combination of the vessels42, 43, 44 can be used in the method of FIG. 4. The addition of thesilicon containing particles and the suspending agent and/or theemulsifying agent leads to significant corn oil coalescence beforeseparation of the corn oil by centrifuging or decantation. Thisincreases the amount of corn oil recovered during separation which canbe accomplished using various means such as centrifuging and/ordecantation.

In the method of FIG. 4, the silicon containing particles in thedispersions are preferably selected from silica, talc, clay,diatomaceous earth, and mixtures thereof. The silicon containingparticles can be precipitated or fumed. The silicon containing particlescan be hydrophilic or hydrophobic. Preferably, the silicon containingparticles are precipitated hydrophilic silica particles. The siliconcontaining particles can have an average particle size of less than 100micrometers, more preferably an average particle size of less than 50micrometers, and most preferably an average particle size of less than20 micrometers.

The silicon containing particles can be present in any of thedispersions at a level of 0.1 wt. % to 30 wt. %, more preferably, alevel of 5 wt. % to 15 wt. %, and most preferably, at a level of up to15 wt. %. The silicon containing particles can be dispersed under highshear in the vessels 42, 43, 44. The silicon containing particles can bedispersed using milling, homogenizing, or ultrasonic means.

In one non-limiting example, the suspending agent is selected from gumsor celluloses. Compounds such as gums or celluloses thicken the mixturein the vessels 42, 43, 44 to prevent the silicon containing particlesfrom settling out.

In one non-limiting example, the emulsifying agent is selected fromsurfactants. Example surfactants include non-ionic surfactants such as:(1) fatty alcohol alkoxylates, especially the ethoxylates, wherein thealkyl group has from 8 to 22 carbons and 5 to 35 moles of alkoxide permolecule; (2) fatty acid alkoxylates having from about 5 to about 35moles of alkoxylate, especially the ethoxylate; and (3) PEG-ylatedsorbitans esterified with fatty acids, commonly known as polysorbates.Non-limiting example polysorbates include polysorbate 20(polyoxyethylene (20) sorbitan monolaurate), polysorbate 40(polyoxyethylene (20) sorbitan monopalmitate), polysorbate 60(polyoxyethylene (20) sorbitan monostearate), and polysorbate 80(polyoxyethylene (20) sorbitan monooleate) wherein the number followingthe polyoxyethylene part refers to the total number of oxyethylene—(CH₂CH₂O)— groups found in the molecule. Most preferably, polysorbate80 is used in the method of FIG. 4. Non-ionic surfactants having carbonchain lengths of 16-18 carbons are quite advantageous.

The suspending agent and/or the emulsifying agent can be present in thedispersion in water at a level of 1 wt. % to 30 wt. %, more preferably,a level of 4 wt. % to 15 wt. %, and most preferably, at a level of up to15 wt. %.

In one embodiment of the method of FIG. 4, pumps 46, 47, 48 arecontrolled such that the mixture of the silicon containing particles andthe suspending agent and/or the emulsifying agent added to the wholestillage and/or the thin stillage and/or the thick stillage create acomposition including silicon containing particles at a level of 0.1 wt.% to 30 wt. %, an emulsifying agent at a level of 1 wt. % to 30 wt. %,and water at a level of 40 wt. % to 99 wt. %. The water-basedcomposition has significantly lower viscosity than other compositions,particularly at temperatures between 32° F. and 50° F.

In one embodiment of the composition used in the method of FIG. 4, thesilicon containing particles are present a level of 1 wt. % to 20 wt. %,the emulsifying agent is present at a level of 1 wt. % to 20 wt. %, andwater is present at a level of 60 wt. % to 90 wt. %. In anotherembodiment of the composition, the silicon containing particles arepresent at greater than 5 wt. % to 15 wt. %, the emulsifying agent ispresent at a level of 4 wt. % to 15 wt. %, and water is present at alevel of 70 wt. % to 90 wt. %. In yet another embodiment of thecomposition, the dispersion consists essentially of silicon containingparticles at a level of greater than 5 wt. % to 15 wt. %, an emulsifyingagent at a level of 4 wt. % to 15 wt. %, and water at a level of 70 wt.% to 90 wt. % thereby avoiding components that adversely affect theamount of corn oil recovered during centrifuging and/or decantation.

While corn oil extraction is shown in FIG. 4, the method is suitable forthe extraction of other oils that are emulsified. For example, the oilcan be a vegetable oil, an animal fat, petroleum oil, and mixturesthereof. The vegetable oil may be emulsified by a biological surfactantcomprising phospholipids and proteins.

EXAMPLES

The following Examples have been presented in order to furtherillustrate the invention and are not intended to limit the invention inany way.

Example 1

Surfactants have the ability to competitively absorb at an air water, oroil water interface, displacing absorbed proteins via an orogenicmechanism. The orogenic mechanism occurs in a number of steps. In thecase of protein stabilized air, a non-ionic surfactant that is morestable than the absorbed protein will add at a weak point in the proteinstabilizing matrix. Surfactant will continue to add to the weak point.As surface pressure builds on the interface, the protein will start tocondense giving way to the more stable surfactant. At some criticalsurface pressure, the protein matrix will collapse releasing the airbubble.

Differences in the number addition sites and the relative surfacepressure leading to matrix collapse were observed for ionic andnon-ionic surfactants. For ionic surfactants, more nucleation sites atthe air water interface were present compared to non-ionic surfactant.This can be attributed to electrostatic repulsion between individualsurfactant molecules. As the initial point of nucleation grows, so doesthe repulsive charge at that site, thus making additional sites ofnucleation more energetically favorable. The difference in surfacepressure could be attributed to the method of nucleation (more sites vs.less sites) or increased surfactant-protein interaction due to chargedsurfactant head groups.

Competitive displacement of oil body proteins with surfactants wasstudied. Differences in non-ionic surfactants were observed usingpolysorbate 20 (polyoxyethylene (20) sorbitan monolaurate) andpolysorbate 60 (polyoxyethylene (20) sorbitan monostearate) wherein thenumber following the polyoxyethylene part refers to the total number ofoxyethylene —(CH₂CH₂O)— groups found in the molecule. While bothsurfactants broke the protein matrix at the same surface pressure, morepolysorbate 60 was needed to get to that pressure. This can beattributed to tighter packing due to polysorbate 60 having a longerhydrophobic chain. This could affect polysorbate 60 efficiency in anumber of ways: polysorbate 60 may have a harder time adding tonucleated sites due reduced monolayer fluidity, more polysorbate 60 mayhave to be absorbed at the interface to displace the same amount space,or polysorbate 60 may diffuse through solution at a slower rate thanpolysorbate 20.

Competitive displacement of oil body protein by polysorbate 80(polyoxyethylene (20) sorbitan monooleate) was also studied. It wasshown that at low levels of polysorbate 80, less stable surface activeproteins called caleosins and steroleosin were displaced. At higherlevels of polysorbate 80, oleosin was displaced, but not completely.This is due to the stability of oleosin relative to other oil bodyproteins.

In general, oil body proteins are more stable than other common surfaceactive proteins like those found in milk or egg yolk. This is importantin context of oil demulsification, since rigorous process conditions(temperature, pH, mechanical action) could cause a portion of the oilbody proteins to become denatured, thus leaving them less surfacestable. Think of an active protein as a ball of yarn. Putting ten ballsof yarn in a box is not a problem, but stretch the yarn out and itquickly becomes a tangled mess.

If some of the proteins are denatured, these proteins would interactwith surrounding proteins more readily, and have been shown to form aviscoelastic mesh, preventing oil coalescence via a surrounding proteinbarrier. This viscoelastic barrier increases emulsion stability inisolated oil bodies that cream rapidly in the absence of such a barrier.Since denatured proteins no longer have the same surface activity, theaddition of a surface active surfactant would selectively kick off thedenatured proteins and allow the oil body to shed its protective proteinbarrier. These newly freed oil bodies, covered by surfactant and intactoil body proteins, would have the ability to collide with one anotherfacilitating the first step of coalescence.

Polysorbate 80 currently out-performs all other surfactants testedincluding polysorbate 20, polysorbate 40 (polyoxyethylene (20) sorbitanmonopalmitate), and polysorbate 60. According to polysorbate 80's rolein the competitive absorption mechanism, that this dominance can beexplained by polysorbate 80's unique optimization of three contributingfactors: interface affinity, packing, and surfactant diffusivity.

Interface affinity indicates the affinity of the surfactant to the oilwater interface. If the surfactant has a higher affinity to theinterface than the protein, the surfactant will competitively displacethe protein. This factor not only has to do with the relative ratio ofhydrophobic to hydrophilic portions (HLB number), but also the size ofthe molecule. A larger molecule, with the exact same HLB number as asmaller molecule, will be have a greater affinity to the interface.Interestingly, phospholipids, the molecules making up the lipid bilayerof all cellular organisms, contain two fatty acid chains with lengthsranging between 14 and 24 carbons long. The composition of corn oil isgenerally 55% linoleic acid (18:2), 23% oleic acid (18:1), and 12%palmitic (16:0). Since the phospholipid bilayer is often representativeof the fatty acids available in the cell, it can be concluded that thephospholipids present are mostly between 16 and 18 carbons long. Thiscould indicate that the surfactant with the maximum chain interactionsleading to the highest interfacial affinity would have chain lengthsbetween 16 and 18 carbons long.

Packing refers to how densely absorbed a surfactant is on an interface.Packing in a bi-lipid membrane, such as the phospholipid membranes foundin cells, is contingent upon packing conditions of the surfactant headand tail groups. The larger hydrophobic head group on polysorbate 80could explain its dominance over other surfactants. Not only would thislarge head take up more area, it also makes the lipid packing ratio <1.This indicates that the molecules hydrophilic head takes up more spacethan the hydrophobic tail, and therefore causes the most stable geometryof the surface to increase in curvature. In addition, the unsaturatedfatty acid hydrophobic tail on polysorbate 80, will pack less tightlythan saturated fatty acid chains (polysorbate 20, polysorbate 40, andpolysorbate 60) and would lead to a membrane that is more fluidic. Afluidic membrane could facilitate surfactant diffusion onto themembrane, thus altering the kinetics of the competitive displacementmechanism in favor of the surfactant.

Example 2

Upon collision, the oil globules will either come together (coalesce) ormove apart. The probability of coalescence depends on the presence ofsurfactant (oil body proteins, phospholipids, polysorbate 80) at the oilwater interface. If the oil is covered in intact oleosins, theprobability of coalescence will be small. If some of these proteins areremoved or denatured, the probability of coalescence will increase.

Hydrophobic precipitated silica particles are porous particles treatedwith siloxane polymer chains. These chains are of variable length andcause the silica to be hydrophobic. Protein buildup on siloxane treatedhydrophobic surfaces is well documented. This is thought to be a resultof hydrophobic interactions, and leads to protein adhesion andsubsequent denaturation on the silica surface.

Without intending to be bound by theory, there are a few different waysin which the silica could be acting. The first is as a fining agent thatremoves protein from the aqueous phase. This could explain theobservation that the oil obtained using the polysorbate 80+silica vs.straight polysorbate 80 appeared less cloudy. Silica may actively stripprotein from oil globules which brush by, or act as a protein-sink inthe polysorbate 80 facilitated protein desorption and transportationaway from the oil-water interface.

Silica could also promote coalescence by providing a surface aroundwhich oil bodies collect and eventually coalesce. Due to its highlyhydrophobic surface, oil has been shown to preferentially wet ahydrophobic silica particle's surface. Therefore with a silica particlepresent, two oil globules which would normally move apart aftercollision would now be stuck together. This would increase their time inclose proximity and thus increase the probability of coalescence.

Example 3

Corn oil demulsification tests were performed. The demulsificationproperties of a dispersion containing 80 wt. % water, 10 wt. %hydrophilic precipitated silica particles, and 10 wt. % polysorbate 80(Dispersion 1) was compared to 100% polysorbate. Dispersion 1 hadsuperior demulsification properties.

The demulsification properties of a dispersion containing 70 wt. %water, 10% hydrophilic precipitated silica particles, and 20%polysorbate 80 (Dispersion 2) was compared to 100% polysorbate.Dispersion 2 had better demulsification properties.

Thus, the invention provides compositions and methods for aiding theextraction of an emulsified oil from an oil and water emulsion. In oneversion of the invention used in a dry-mill ethanol process, significantcorn oil coalescence can occur before separation of the corn oil bycentrifuging or decantation. This increases the amount of corn oilrecovered during centrifuging and/or decantation.

Although the present invention has been described in detail withreference to certain embodiments, one skilled in the art will appreciatethat the present invention can be practiced by other than the describedembodiments, which have been presented for purposes of illustration andnot of limitation. Therefore, the scope of the appended claims shouldnot be limited to the description of the embodiments contained herein.

What is claimed is:
 1. A composition for aiding extraction of anemulsified oil from an oil and water emulsion, the compositioncomprising: silicon containing particles; an emulsifying agent selectedfrom the group consisting of fatty alcohol alkoxylates and fatty acidalkoxylates; and water.
 2. The composition of claim 1 wherein: thesilicon containing particles are present at a level of 0.1 wt. % to 30wt. %; the emulsifying agent is present at a level of 1 wt. % to 30 wt.%; and water is present at a level of 40 wt. % to 99 wt. %.
 3. Thecomposition of claim 1 wherein: the silicon containing particles arepresent at greater than 5 wt. % to 15 wt. %; the emulsifying agent ispresent at a level of 4 wt. % to 15 wt. %; and water is present at alevel of 70 wt. % to 90 wt. %.
 4. The composition of claim 1 wherein:the silicon containing particles are selected from the group consistingof silica, talc, clay, quartz, diatomaceous earth, and mixtures thereof.5. The composition of claim 1 wherein: the silicon containing particlesare precipitated silica particles.
 6. The composition of claim 4wherein: the silicon containing particles are hydrophilic.
 7. Thecomposition of claim 1 wherein: the silicon containing particles have anaverage particle size of less than 100 micrometers.
 8. The compositionof claim 1 wherein: the emulsifying agent is selected from the groupconsisting of fatty alcohol alkoxylates.
 9. The composition of claim 1wherein: the emulsifying agent is selected from the group consisting offatty alcohol ethoxylates having an alkyl group from 8 to 22 carbons and5 to 35 moles of alkoxide per molecule.
 10. The composition of claim 1wherein: the emulsifying agent is selected from the group consisting offatty acid alkoxylates.
 11. The composition of claim 1 wherein: theemulsifying agent is selected from the group consisting of fatty acidethoxylates having from about 5 to about 35 moles of ethoxylate.
 12. Amethod of extracting oil from an oil and water emulsion in a material,the method comprising: (a) adding the composition of claim 1 into thematerial; and (b) separating the oil from the material.